In cold weather conditions, it is known that the fluid within pipes, such as water mains, drain lines, storm drains and sewers, which does not flow continuously is likely to freeze, thereby causing a blockage of the pipe. One solution is to chemically change the properties of the fluid flowing through the pipe so as to reduce its tendency to freeze in cold conditions. However, this can have an adverse effect on the liquid being transported and it is not usually feasible or economical.
Another solution is to heat the contents within the pipe so as to counteract the external environmental conditions. Such a solution can include using heat blankets positioned on the outside of the pipe. This is only possible when the pipe is easily accessible. Another option is to use specialty pipes with heated wires permanently located or fixed on the interior or exterior surface of the pipes to increase the temperature of the fluid so as to prevent freezing. This may also not be feasible for existing pipes as it would require replacing the pipes altogether and would be costly for most consumers. Furthermore, as it is difficult to remove the wire from the pipe or to access the wire within the pipe, repair or maintenance of the wire located within the pipe is problematic. Where the wire is located adjacent the surface of the pipe, it may also be vulnerable to normal procedures used for cleaning the pipe in which the wire is installed as threading a cleaning tool through a pipe can often damage the wire rendering it inoperable.
In another option, customers may seek to heat the pipe locally from the exterior (e.g. by applying a heat source) but localised heating may cause damage to the pipe as the ice thaws.
In general, many current waste water systems are prone to freezing during winter and require a method to provide a reliable pipe freeze protection. The only current CSA approved solution is to install a heating cable on the outside of the pipe. However, such cables may make only point contact with the outside of the pipe and may cause localised damage to the pipe or may cause localised boiling of liquid in the pipe. As a result, thermal insulation of the pipe is avoided, leading to high energy consumption for the cable.
It has been proposed to insert a heating cable within a pipe and control the current to the heating cable to prevent freezing. This has proven to be a viable solution in the supply of water to residential units where burial of the supply line is impractical. The cable is surrounded by the water which dissipates heat within the pipe and avoids localised overheating. As such, the exterior of the pipe may be insulated without risking damage to the pipe itself.
Whilst the above arrangement is satisfactory for water supply, and has CSA approval, it cannot be used in an environment such as sewer lines and septic fields where explosive or inflammable gas may be present, or under conditions where high pressures may be encountered, such as a high pressure water main.
Therefore, it is an object of the present invention to obviate or to mitigate at least some of the above presented disadvantages.